World's First Helicopter – Today in History: September 14 - Connecticut History | a CTHumanities Project
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British Pathé on X: "The 24 May also marks the 80th Anniversary of the first single-rotor helicopter flight, made by Igor Sikorsky. Sikorsky's pioneering rotor configuration is the basis for those in
Sikorsky XR-4 Helicopter | Smithsonian Institution
First helicopter by Igor Sikorsky | Sikorsky, Igor sikorsky, Helicopter
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Helicopter - Wikipedia
Aviation History - First Helicopter Flight-November 13, 1907 - Flight Journal
The Helicopter: A Hundred Years of Hovering | WIRED
AH-1G Cobra (early production) US Attack Helicopter (100% new molds) ICM 32060
The Helicopter: A Hundred Years of Hovering | WIRED
How Sikorsky's first helicopter took flight in CT: Getting There
HavKar : When Was The First Helicopter Invented
Igor Sikorsky Built His First Helicopter Before the Wrights Flew – Disciples of Flight
Helicopter | Facts, History, & Types | Britannica
